*{
    margin: 0;
    padding: 0;
}
a{
    text-decoration:none;
    color: #999;
}
li{
    list-style: none;
}
body{
    background-color: #f4f4f4;
}
/* 大屏幕 */
@media only screen and (min-width:1200px) {
    html{
        font-size: 20px;
    }
}
/* 中等屏幕 */
@media only screen and (max-width: 1199px) {
    html{
        font-size: 16px;
    }
}
.width{
    width: 60rem;
}